Method and apparatus for harvesting and implanting bone plugs

ABSTRACT

A system for transplanting a bone plug from a donor site to a recipient site extracts the bone plug from the donor site, and then places a bone plug delivery device having a tip which is at least translucent and, preferably, clear over a tube containing the bone plug. The tip is then placed substantially over a pre-formed hole in the recipient site, whereafter the bone plug is forced from the tube, through the transparent tip, and into the pre-formed hole.

BACKGROUND OF THE INVENTION

[0001] The present invention is directed to methods and apparatus forharvesting and implanting bone plugs. The invention has particularutility in repairing damaged bone tissue, such as articular cartilageand underlying subchondral cancellous bone in the knee and otherweight-bearing joints.

[0002] Weight-bearing joints, such as the knee, are particularlysusceptible to injuries caused by friction between opposing bonesurfaces. To understand the causes of such injuries, it is firstnecessary to understand the anatomy of a such a joint. In this regard,FIG. 1 illustrates knee joint 10. As shown in FIG. 1, knee joint 10connects femur 12 to tibia 14 and fibula 18 via connective tissue 15 and17 Interposed between opposing surfaces of femur 12 and tibia 14 arelateral and medial meniscus cartilages 21 and 23, respectively. Condyles22 at distal end 11 of femur 12 are supported by meniscus cartilages 21and 23 on proximal end 13 of tibia 14. Normally, distal end 11 of femur12, including condyles 22, is covered by layer 28 of cartilaginousmaterial which is about 5 mm thick. This layer 28 is called thearticular cartilage.

[0003] Articular cartilage 28 forms a generally resilient pad which isfixed to distal surface 11 of femur 12 in order to protect femur 12 fromwear and mechanical shock. When lubricated by fluid in knee joint 10,articular cartilage 28 provides a surface which is readily slidable onthe underlying surfaces of meniscus cartilages 21 and 23 or on proximalsurface 13 of tibia 14 if one or both of meniscus cartilages 21 and 23is partially or totally absent. Problems arise, however, if articularcartilage 28 becomes injured due to excessive near. For example,articular cartilage 28 can become torn or thin, or holes can developtherein. As a result of such injuries, osteochondritis and/or arthritiscan develop, making movement of the joint painful In extreme cases,these conditions can result in disability if not treated.

[0004] Injuries of the foregoing type can be treated by replacing thejoint, or portions thereof, with artificial materials. In some cases,however, it is possible to treat the injury by replacing only the bonetissue (i.e., the articular cartilage and/or underlying bone) at thesite of the injury with a graft, or plug, from a healthy site. Thisoption is preferable for a number of reasons. For example, surgery totransplant a bone plug is less invasive than that required for a jointreplacement. In fact, bone plug transplant surgery is typicallyperformed arthroscopically. Moreover, transplanting bone plugs leads tofewer post-operative complications, a shorter rehabilitation period, andbetter results overall, since it actually leaves patients with theiroriginal joint intact.

[0005] Surgical techniques for transplanting bone plugs typicallyinvolve removing the damaged bone tissue by drilling or cutting a holeat the site of the damage, and plugging this hole with a bone plugextracted from healthy bone tissue in the patient's body. This healthytissue is generally extracted from non-load-bearing joints or surfacesin order to minimize patient substantial discomfort.

[0006] Surgical instruments are currently available which may be used toharvest or extract a bone plug from a donor site and, then, to implantit into a pre-formed hole at a recipient site. A conventional harvestinginstrument typically includes a tube having a cutting edge at the distalend. To extract a plug, the instrument is driven into the bone at thedonor site and then removed, taking with it a plug of healthy bonetissue.

[0007] The conventional instruments for harvesting bone plugs describedabove suffer from several drawbacks. For example, it is difficult toregulate the size (i.e., the length) of bone plugs extracted by them.Moreover, the bone plug tissue is sometimes unduly damaged ortraumatized by excessive forces exerted during extraction orimplantation.

[0008] Conventional instruments for implanting bone plugs also sufferfrom drawbacks. Generally, it is difficult to gauge the exact depth ofplug insertion and, thus, to avoid slight protrusions or cavities. Thisproblem is compounded in those instances where the donor and recipientsites do not have matching surface contours.

[0009] Thus, there exists a need for a bone plug harvesting apparatuswhich can be more easily used to remove plugs of bone, and which enablesa surgeon to regulate the size of the bone plug being removed. Inaddition, there exists a need for a bone plug implantation apparatuswhich permits the plug to be implanted level and in proper alignmentwith the surrounding bone.

[0010] In view of the foregoing, an object of the invention is toprovide improved methods and apparatus for harvesting and implantingbone plugs.

[0011] Another object is to provide such methods and apparatus as topermit the size of extracted plugs to be better regulated.

[0012] Still another object of the invention is to provide such methodsand apparatus as to minimize trauma to the transplanted plugs.

[0013] Still another object is to provide such methods and apparatus asto facilitate accurate placement of bone plugs during implantation.

[0014] Yet still another object is to provide such methods and apparatusas to facilitate implantation in instances where the plugs or recipientsites have uneven contours.

SUMMARY OF THE INVENTION

[0015] The present invention addresses the foregoing needs by providing,in one aspect, a bone plug implantation apparatus having a translucentand, preferably, a transparent or clear tip, through which the bone plugcan be viewed during implantation. Unlike the prior art, inclusion ofsuch a tip permits the surgeon to view the bone plug duringimplantation, thereby facilitating better placement, alignment andinsertion of the plug into the donor site.

[0016] According to further aspects of the invention, the apparatusincludes a “harvesting” tube which can be used to harvest the plug andwhich is used to hold the bone plug prior to implanting. The apparatuscan also include a push rod that forces the bone plug into a pre-formedhole at the transplant site. The harvesting tube can include an apertureor recessed inner wall that reduces friction on the plug duringimplantation (and harvesting) and that, thereby, reduces undesirablecompression of the plug.

[0017] According to further aspects of the invention, the tip has aninner diameter substantially equal to that of the hole into which thebone plug is transplanted. An outer diameter of the tip, however, can begreater than that of the hole. This larger outer diameter forms ashoulder upon which the tip can rest during implantation. The tip alsocovers the distal end of the harvesting tube and, hence, minimizes thedamage that it might otherwise cause at the transplant site.

[0018] In still further aspects of the invention, the tip is rotatablerelative to the harvesting tube. This facilitates rotation of the boneplug relative to the transplant site, e.g. so that their respectivesurfaces can be aligned and otherwise better fitted

[0019] According to still another aspect, the present invention providesan apparatus for harvesting plugs from bone tissue. The apparatusincludes a harvesting tube, as described above, to which a cuttingsheath is fitted. The sheath, which includes a cutting edge and acutting tooth, can include markings on its outer surface so that thedepth of insertion—and, therefore, the length of the bone plug—can bedetermined during harvesting. The harvesting tube can likewise includemarkings on its outer surface, e.g., adjacent the aforementioned window,so that the position and length of the plus can be more accuratelydetermined after harvesting.

[0020] According to still another aspect, the present invention providesa method of transplanting a bone plug from a donor site to a recipientsize. The method includes harvesting the bone plug from the donor siteutilizing a bone plug harvesting apparatus as described above. Theharvesting tube of the harvesting apparatus is fitted with a tip asdescribed above to form a bone plug implantation apparatus, also asdescribed above. The tip of the implantation apparatus is placed over apre-formed hole at the recipient site and the bone plug is forced fromthe tube, through the transparent tip, and into the pre-formed hole. Inrelated aspects of the invention, the tip is rotated prior toimplantation to assure a better fit.

[0021] Still further aspects of the invention provide a drill guide foruse in bone plug removal and replacement. The guide comprises a tip anda harvesting tube as described above. A drill bit is guided through theassembled tube/tip and is used to form a hole at the recipient site. Useof such an assembly as a drill guide can improve the integrity of thetransplant, e.g., if the same (or similar) tube and tip are subsequentlyused during implantation of the plug.

[0022] This brief summary has been provided so that the nature of theinvention may be understood quickly. A more complete understanding ofthe invention can be obtained by reference to the following detaileddescription of the preferred embodiments thereof in connection with theattached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0023] A more complete understanding of the invention may be attained byreference to the drawings, in which:

[0024]FIG. 1 shows the anatomy of a knee joint;

[0025]FIG. 2 shows a representative embodiment of a harvesting tube usedin a bone plug harvesting apparatus in accordance with the presentinvention;

[0026]FIG. 2A shows a top view of the apparatus shown in FIG. 2;

[0027]FIG. 2B shows a bone plug harvesting apparatus according to theinvention.

[0028]FIGS. 3 and 4 show cutting teeth used in the apparatus of FIG. 2B;

[0029]FIGS. 5 through 10 depict a method for harvesting a bone plugusing the apparatus shown in FIG. 2B;

[0030]FIGS. 11 through 13 show components of a bone plug implantationapparatus of the present invention;

[0031]FIG. 14 shows a bone plug implantation apparatus of the presentinvention:

[0032]FIG. 15 shows damaged bone tissue comprised of articular cartilageand underlying bone;

[0033]FIGS. 16 through 21 depict a method of implanting a bone plugusing the apparatus shown in FIG. 14.

[0034] FIGS. 22-23 show drill guides according to the invention forforming bone holes.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

[0035]FIGS. 2 and 2B are front views of a device 30 according to theinvention for harvesting a plug of bone tissue (i.e., bone and/orarticular cartilage) from a donor site. Illustrated device 30 isgenerally configured in the manner of the harvesting apparatus describedin co-pending, commonly assigned U.S. patent application Ser. No.08/866,830, filed May 30, 1997, the teachings of which are incorporatedherein by reference. The harvesting device 30 incorporates improvementson the apparatus of that prior application, as described below andelsewhere herein.

[0036] The device 30 includes harvesting tube 31, connector 32, handle33, and cutting sheath 35. As shown in FIG. 2, handle 33 is attached toproximal end 34 of tube 31 and is used to facilitate driving the distalend of the device into the donor site and rotating the device to removethe plug. Illustrated handle 33 can be rod-like in construction, asillustrated, or it can be of other configurations, such as a knurledknob, hexagonal nut, or the like. 7 A connector 32 disposed at thejunction of handle 33 and tube 31 includes axial threads 36, asillustrated, to facilitate affixing a cutting sheath or, alternatively,a delivery tip to the harvesting tube. Of course, connector 32 is notlimited to the configuration shown in FIG. 2 but, rather, can be ofother configurations sufficient to support the uses described below

[0037] Tube 31 is substantially cylindrical in shape and is made ofsurgical stainless steel or other material suitable to be driven intobone and used for plug extraction, as described below Tube 31 has aninner bow 39 (se FIG. 2B) extending at least part way (and, preferable,all the way) along longitudinal axis A-A thereof (including throughhandle 33 and connector 32 as shown in FIG. 2A). The bore 39 has adiameter sized in accord with the bone plugs to be harvested. A taperededge 41 at the distal end of the tube 31 which facilitates movement of abone plug (i.e., articular cartilage and/or underlying bone) into andout of inner bore 39.

[0038] Referring to FIG. 2B, device 30 also includes cutting sheath 35that, too, is fabricated from surgical stainless steel or other suitablematerial. The sheath includes, at its distal end, tooth 43 and cuttingedge 48. An inner bore receives tube 31 in the manner shown in FIG. 2B.The proximal end (e.g. the hub) 38 of sheath 35 includes threading orother structures for mating with corresponding threading 36 on connector32.

[0039] The outer surface of cutting sheath 35 may also include one ormore markings 35 b, as shown in FIG. 2B, to facilitate determination ofa depth to which tube 31 and cutting sheath 35 are inserted into bonetissue and, thereby, to facilitate estimating the length of a harvestedbone plug. In preferred embodiments of the invention, there are aplurality of such markings on cutting sheath 35, each of which isseparated by a predetermined distance which, in preferred embodiments ofthe invention is roughly 5 mm.

[0040] Tooth 43, coupled (e.g., welded, clued or integrally formed)substantially at or near distal end 40 of sheath 35, extends into innerbore 39 in a direction substantially orthogonal to cutting edge 48 asshown. By rotating the tube 31, tooth 43 undercuts the bone within thebore 39 and, thereby, facilitates removal of the bone plug. Although aplurality of such teeth may be used in the present invention, preferredembodiments thereof include only one such tooth.

[0041]FIGS. 3 and 4 show front views of tube 31, cutting sheath 35,inner bore 39 and tooth 43 taken along ling B-B of FIG. 2B Referring toFIG. 3, tooth 43 is preferably rectangular in shape, though it may be ofother configurations, e.g., triangular (as shown in FIG. 4) The tooth 43has a length which is roughly 1 16 to ¼ the diameter of inner bore 39,with the most preferred length being roughly ⅕ of the diameter of innerbore 39.

[0042] Turning back to FIGS. 2 and 2B, tube 31 includes at least onerecess 45 cut at least partway from an inner surface of tube 31 to anouter surface. This may comprise an indentation or, preferably, a windowor aperture cut entirely through tube 31. To avoid unduly weakening thetube 31, recess 45 is spaced apart from its distal end.

[0043] Recess 45 is positioned so that at least a portion of itpenetrates a patient's bone tissue during bone plug extraction. In thisregard, the recess 45 reduces frictional contact between the bone plugand the inner surface of the tube 31. This has the advantage of reducingundesirable compression of the plug during extraction and subsequentemplacement. Though the illustrated embodiment incorporates only asingle recess 45, those skilled in the art will appreciate that multiplerecesses (e.g., windows) of varying (or the same) configuration may beused.

[0044] As further shown in the drawing, the outer surface of tube 31 mayalso include one or more markings, as shown in close-up view 46 in FIG.2. In the illustrated embodiment, these markings are substantiallysimilar to those contained on cutting sheath 35 and described above.When used in conjunction with a window-like recess 45, these markingsfacilitate determination of the length and position of the bone plug.

[0045] FIGS. 5 to 10 depict the distal end of device 30 during asurgical procedure for harvesting a bone plug in accordance with thepresent invention. By way of overview, they show the driving of tube 31and cutting sheath 35 into donor site 50, the rotation of the tube toundercut the bone plug with tooth 43 and the removal of the tube 31 withthe bone plug The surgical techniques shown in these drawings aretypically performed arthroscopically using conventional equipment,although open surgical techniques may be used as well

[0046] In detail, FIG. 5 shows a close-up view of the distal end ofdevice 30 (i.e., the distal end of cutting sheath 35 and the distal endof tube 31) prior to contact with donor site 50. In this case, donorsite 50 comprises bone tissue made up of both articular cartilage andunderlying bone, such as the intracondylar notch or the periphery of thecondyle. It should be noted, however, that the invention can also beused with cartilage-only and with bone-only sites, as well as with otherappropriate bodily structures.

[0047]FIGS. 6 and 7 show penetration of device 30—in particular, thedistal end of tube 31 and cutting sheath 35—into donor site 50. Cuttingedge 48 slices through donor site 50 to separate the bone plug 52 fromsurrounding tissue 54. Tapered edge 41 of tube 31 facilitates movementof bone tissue into inner bore 39 of tube 31.

[0048] Once tube 31 has been driven into donor site 50 a desired depth,e.g., as determined from markings 35 b, the bone plug 52 is furtherseparated from the surrounding tissue by rotating device 30 (and, moreparticularly, cutting sheath 35) to undercut the plus 52, as shown inFIG. 8. Once rotated a complete (or near-complete) revolution, thedistal end of device 30 is pulled from donor site, taking bone plug 52with it. This is shown in FIGS. 9 and 10.

[0049] After extraction of the plug 52, cutting sheath 35 is removed(e.g., unscrewed and removably slid from) tube 31, leaving bone plug 52in tube 31. Bone plug 52 may then be implanted from tube 31 into arecipient site using the implantation apparatus shown in FIG. 14, theseparate components of which are shown in FIGS. 11 to 13

[0050] At the outset, the implantation apparatus includes a harvestingtube 31 similar and, preferably identical to that shown in FIG. 2 anddescribed above. For sake of completeness, that tube is redrawn in FIG.11.

[0051] The implantation apparatus further includes a delivery tip 67that facilitates transfer of the bone plug into a pre-formed hole in therecipient site. The tip 67, which is attachably affixed to the distalend of the tube 31 is “at least translucent,” i.e., it is translucentor, preferably, transparent and, still more preferably, clear. In thisregard, the tip 67 is preferably fabricated from surgical gradeplastics, or the like.

[0052] Tip 67 can be affixed to tube 31, via threading, friction fit orother known mechanism, so that its inner bore 101 is substantiallyaligned with inner bore 39 at the distal end of tube 31. In thepreferred embodiment, the tip is part of a one-piece, molded devicewhich also includes a sheath-like portion—referred to below as proximalsegment 66—that slips over tube 31 and screws onto connector 32 (e.g.,in the same manner as the cutting sheath discussed above) via connector71. Like tip 67, the proximal segment 66 of the illustrated embodimentis also fabricated from materials that are at least translucent (and,preferably, clear). Together, the tip 67 and proximal segment 66 arereferred to as delivery sheath 65.

[0053] Of course, the invention is not limited to using a one-piece,molded device as its delivery sheath. For example, the delivery sheathcan be a two-piece device comprised of a tip and a tube which fastentogether, e.g., via screw threads or the like.

[0054] Referring to FIG. 12, proximal segment 66 has an inner bore 100with a diameter substantially similar to, but somewhat larger than, anouter diameter 70 of tube 31. This permits segment 66 to fit over tube31 without substantial lateral play. Preferably, the connector 32 and/orconnector 71 are mated to one another so as to permit rotation of thesheath 65 (and, more particularly, the tip 67) relative to the tube 31.In the illustrated embodiment, the mating threads of corrector 32 andconnector 71 permit it such rotation (e.g., via clockwise orcounterclockwise motion of one relative to the other) Alternativeembodiment may incorporate bearings, floating or sliding surfacesinstead.

[0055] Tip 67 preferably has an inner bore 101 with a diameter thatsubstantially corresponds to that of inner bore 39 of the distal end ofharvesting tube 31. In preferred embodiments, this also correspondssubstantially to the inner diameter of the plug-receiving cavity at therecipient site.

[0056] The outer diameter of at least the distal end of the tip 67,however, is preferably larger than the inner diameter of the cavity. Thesurface of the tip 67 at the distal end is preferably smooth, so as toprevent marring of the bone tissue surface, though it may include afriction-enhancing coating or structure (e.g., protrusions) to helpmaintain alignment of the bores 39 and 101 with the recipient cavityduring the procedure.

[0057] The tip 67 and, more particularly, inner bore 101 has a lengththat permits at least a portion of the bone plug 52 to be seen duringthe implantation procedure. Thus, in preferred embodiments, the bore 101has a length of 1 to 50 mm and, preferably, about 10 mm. Of course, thediameter of bore 101, like that of the distal end of tube 31 and therecipient cavity, substantially matches the expected diameter of thebone plug 52.

[0058] The junction of bores 100 and 101 forms a chamfered or flatshoulder adjacent to, or upon which, the distal end of tube 31 isdisposed. This prevents the tube 31 and, particularly, its tapereddistal end, from directly contacting, and potentially marring, thesurface of the recipient site. In this regard, preferably, the distalend of tube 31 does not actually contact the shoulder. Instead, edge 41is held just proximal of the shoulder (i.e., by connector 71 and threads34) so as to permit transfer of a bone plug into the tip

[0059] Referring to FIG. 13, the illustrated implantation apparatusincludes push rod 74 that slides, reciprocates or otherwise moves withininner bore 39 of tube 31 to push bone plug 52 through the tip 67 andinto the recipient bore hole. To this end, the rod 74 is long enough andotherwise sized to permit complete evacuation of the plus from the bores39 and 101. The distal end of rod 74 is preferably sized and shaped(e.g., flat) to effect little or no damage to bone plug 52 during itscontact therewith. To prevent the push rod from moving into tube 31, therod 74 preferably has a head 77 greater in diameter than inner bore 39.

[0060] The following describes implantation of a bone plug into arecipient site using the implantation device shown in FIGS. 11 to 14. Asbefore, this surgical technique is preferably performed arthroscopicallyusing conventional equipment, although open techniques may be utilizedas well. Implantation is generally performed in the manner described inthe aforementioned incorporated-by-reference application, as modified toaccommodate the improvements described herein.

[0061] To begin, FIG. 15 shows a defect or damaged area 79 in articularcartilage 80 of the type amenable to repair using the method andapparatus of the present invention. Prior to implantation, the defect ordamaged area is removed and a hole for the bone plug is formed.

[0062] This may be accomplished in a variety of ways known in the art.Preferably, however, the bone hole itself is formed using the harvestingtube 31 and/or delivery sheath 65 as a drill guide. More specifically,the tube 31 and sheath 65 (with substantially clear tip 67) areassembled and placed over the recipient site. A drill bit, having anouter diameter which is substantially the same as bore 39, is thenpassed through bores 39 and 101 and applied to form a hole in the bone.FIG. 23 shows drill bit 150 of drill 151 forming a bone hole in thismanner. Alternatively, the tip of delivery sheath 65 alone may be usedto form the bone hole FIG. 22 shows drill bit 152 of drill 153 forming abone hole in this manner In this regard, forming a bone hole using drillguides having a substantially clear tip facilitates formation of boneholes normal to the bone surface or at other desired angles. It alsoensures better aliment between the bone plug implanting device and thehole at the recipient site. That is, because the drill bit can be viewedthrough the clear tip, it is possible to align the drill bit moreaccurately than has heretofore been possible. This step is, of course,performed prior to harvesting the replacement bone plug 52 or,alternatively, is performed using a harvesting tube 31 other than thatin which a harvested plug 52 is contained.

[0063] Once the bone hole has been formed and the replacement bone plughas been harvested, the implantation apparatus is assembled by slidingthe delivery sheath 65 over the harvesting tube 31. The assembledapparatus is then placed so that the bore 101 substantially aligns withbone hole 87, and so that edge 88 of tip 67 (i.e., that portion whichsurrounds the inner bore) rests on the surrounding bone tissue surface(i.e., on the articular cartilage covering the underlying bone).

[0064] If desired, the rod 74 may be used to move the bone plug 52 atleast partially into tip 67 prior to placement of the implantationapparatus. Indeed, the bone plug 52 may be partially extruded, e.g., 1mm to 2 mm, from the tip 67 to facilitate its alignment and insertioninto the bone hole 87. The bone plug 52, moreover, can be rotated forbetter alignment with the hole. This may be accomplished by rotating theimplantation device as a whole or, preferably, by rotating just theimplantation sheath 65.

[0065]FIG. 17 shows the beginning of the implantation process, with pushrod 74l forcing bone plug 52 from the inner bore 39, into tip 67 andjust into bone hole 87. As additional downward pressure is applied topush rod 74 bone plug 52 is forced further into the bone hole Onceagain, the plug 52 may be oriented before it is fully implanted. e.g.,to obtain a better alignment to the bone surface contour, by rotatingthe implantation sheath 65 relative to the harvesting tube 31.

[0066] In this latter regard, since tip 67 is clear, the surgeon is ableto view at least part of, and preferably the entirety of, the plug 52during implantation. In the example shown in FIG. 18, the surgeon willsee that top surface 91 of bone plug 52 does not align with surface 94of the recipient site. Accordingly, as shown in FIG. 19, the sheath 65is rotated in the direction of arrow 95 for proper orientation. Oncealignment has been achieved, the push rod 74 can be tapped to finalizethe implant, as shown in FIG. 20. Thereafter, tube 31 and device 65(including push rod 74) are removed from the site, as shown in FIG. 21.

[0067] In a preferred embodiment, bone plug 52 and corresponding bonehole 87 are sized for an interference fit, so as to reduce the chancesthat the bone plug will inadvertently dislodge from the bone hole. Inthis regard, although the bone plug preferably has an interference fitin the bone hole, several alternative methods are available formaintaining the bone plug in the bone hole. One such technique involvessewing sutures through peripheral edges of the articular cartilageadhering to the bone plug and the surrounding articular cartilagetissue. Alternatively, an adhesive layer (not shown) may be providedbetween bone plug 52 and bone hole 87. This adhesive layer allows timefor sufficient ingrowth of tissue from the surrounding environment sothat bone plug 52 may become locked into place in bone hole 87. Variousbioadhesives are well known in the art, examples of which are fibrinogenand thrombin sealant (see, e.g., U.S. Pat. No. 5,067,964).

[0068] Bone-growth and cartilage-growth promoting chemical factors mayalso be added to the bone hole and/or to the implanted bone plug inorder to promote rapid reconnection of the bone plug to the surroundingbone and articular cartilage. These bone-growth and cartilage-growthpromoting chemical factors may include cartilage-derivedcolony-stimulating factor (“CDGF”) (see U.S. Pat. No 5,376,636), variousinterleukins, colony-stimulating factor (“CSF”), osteopontin,platelet-derived growth factor (“PDGF”), and bone morphogenic protein(“BMP-1”). See also U.S. Pat. No. 5,373,503, the contents of which arehereby incorporated by reference into the subject application as if setforth herein in full.

[0069] The present invention has been described with respect toparticular illustrative embodiments. It is to be understood that theinvention is not limited to the above-described embodiments andmodifications thereto, and that various changes and modifications may bemade by those of ordinary skill in the art without departing from thespirit and scope of the appended claims.

In view of the foregoing, what we claim is:
 1. An apparatus forharvesting plugs from bone tissue, the apparatus comprising: a tubehaving an inner bore running at least part-way therethrough forreceiving a bone plug, the tube having (i) proximal and distal ends,with the distal end having a cutting edge courled thereto for harvestingthe bone plug from the bone tissue, and (ii) at least one recess thatextends at least part way from an inner surface of the tube to an outersurface of the tube; and a tooth, coupled substantially at the distalend of the tube and extending towards the inner bore in a directionsubstantially orthogonal to the cutting edge, for cutting the bone in adirection substantially orthogonal to the cutting edge in order toextract the bone plug.
 2. An apparatus according to claim 1, furthercomprising a sheath that includes the cutting edge and the tooth, thesheath being mated to the tube and including one or more markings on anouter surface thereof, the one or more markings corresponding to anamount that the sheath is inserted into the bone tissue.
 3. An apparatusaccording to claim 1, wherein the at least one recess runs toward theproximal end of the tube and begins a predetermined distance away fromthe distal end of the tube.
 4. An apparatus according to claim 3,wherein the recess comprises an aperture.
 5. An apparatus according toclaim 1, wherein the tube includes a plurality of recesses that extendat least part way from an inner surface of the tube to an outer surfaceof the tube, each of which runs toward the proximal end of the tube andbegins a predetermined distance away from the distal end of the tube. 6.An apparatus according to claim 1, further comprising a handle attachedto the proximal end of the tube for driving the tube and the tooth intothe bone.
 7. An apparatus according to claim 1, wherein the bone plugcomprises articular cartilage and underlying bone tissue.
 8. Anapparatus for implanting a bone plug into a pre-formed hole in bonetissue, the apparatus comprising a tip, through which the bone plug isguided into the pre-formed hole, wherein at least a portion of the tipis at least translucent.
 9. An apparatus according the claim 8, whereinat least a portion of the tip is any of translucent and clear.
 10. Anapparatus according to claim 9, wherein the tip comprises a surgicalgrade plastic.
 11. An apparatus according to claim 10, furthercomprising a push rod which is moveable relative to the tip, and whichis used to push the bone plus through the tip and into the pre-formedhole.
 12. An apparatus according to claim 11, farther comprising a tubehaving an inner bore which holds the bone plug, the tube being coupledto the tip such that the inner bore of the tube is substantially alignedto an inner bore of the tip; wherein the push rod is slidably disposedwithin the inner bore of the tube so as to force the bone plug from theinner bore of the tube, through the tip, and into the pre-formed hole.13. An apparatus according to claim 12, wherein the tube is slidablycoupled to the tip.
 14. An apparatus for implanting bone plugs into apre-formed hole in bone tissue, the apparatus comprising: a tube havingan inner bore for storing an extracted bone plug; a push rod, having adiameter less than or equal to a diameter of the inner bore of the tube,for contacting the bone plug in the inner bore of the tube and forforcing the bone plug out of the inner bore of the tube; and a tip,which is attached to a distal end of the tube, for receiving the boneplug and for delivering the bone plug to the preformed hole, wherein atleast a portion of the tip is any of translucent, transparent and clearso as to permit visualization of the bone plug as it is being implantedin the pre-formed hole.
 15. An apparatus according to claim 14, whereinthe tip is rotatable relative to the tube.
 16. An apparatus according toclaim 14, wherein the push rod includes a head having a diameter whichis greater than a diameter of the inner bore of the tube.
 17. Anapparatus according to claim 14, wherein the inner bore of the tube runsat least part-way therethrough for storing the bone plug, and the tubehas at least one recess that extends at least part way from an innersurface of the tube to an outer surface of the tube.
 18. An apparatusaccording to claim 17, wherein the recess comprises an aperture.
 19. Anapparatus according to claim 14, wherein the bone plug comprisesarticular cartilage and underlying bone tissue.
 20. A method oftransplanting a bone plug from a donor site to a recipient site, themethod comprising the steps of: harvesting the bone plug from the donorsite; attaching a tip at least a portion of which is at leasttranslucent over a tube containing the bone plug; placing the tipsubstantially over a pre-formed hole in the recipient site; forcing thebone plug from the tube, through the transparent tip, and into thepre-formed hole.
 21. A method according to claim 20, further comprisingthe step of rotating the tip relative to the tube.
 22. A methodaccording to claim 20, wherein the tube comprises an inner bore, acutting edge coupled to the tube, and a tooth coupled to the cuttingedge, the tooth extending towards the inner bore in a directionsubstantially orthogonal to the cutting edge; and wherein the harvestingstep comprises the steps of: driving the tube into the donor site,cutting-edge-first; rotating at least the cutting edge so that the toothcuts through the bone so as to separate at least part of a bottomsurface of the bone plug from the donor site; and removing the tubecontaining the bone plug from the donor site.
 23. A method according toclaim 22, further comprising the step of determining an amount that thedriving step has driven the tube into the first area of the bone byreading one or more markings disposed relative to the cutting edge. 24.A method according to claim 20, wherein the bone plug comprisesarticular cartilage and underlying bone tissue.
 25. A method accordingto claim 20, further comprising, before the harvesting step, the step offorming the pre-formed hole using at least the tip.
 26. A methodaccording to claim 25, wherein the forming step forms the pre-formedhole by placing the tube from within the bone plug delivery device overthe recipient site, passing a drill bit through the tube, and drillingthrough bone tissue at the recipient site via the tube.
 27. A methodaccording to claim 26, further comprising the step of adjusting an angleof the drill bit based on a view of the drill bit as the drill bitpasses through the tip.